1. Field of the Invention
The present invention relates to a display device and a manufacturing method therefor, and more particularly to a display device having organic EL (electro Luminescent) elements and a manufacturing method for the display device.
2. Description of the Related Art
In recent years, a next-generation display has been actively developed in the field of a display device, wherein space saving, high luminance, low power consumption, etc. are demanded. As such a display device, an organic EL display using organic EL elements has now received attention. Such an organic EL display is of a self-luminous type, so that the viewing angle is wide and no backlight is demanded. Accordingly, this display has various features such that power saving can be expected, responsiveness can be increased, and the thickness of the device itself can be reduced.
Generally, in manufacturing an organic EL display, organic EL elements are formed on a drive substrate, and a sealing substrate is next bonded to the drive substrate so as to seal the organic EL elements, thereby obtaining a sealing structure such that the organic EL elements are isolated from the atmosphere. The reason for providing such a sealing structure is that the organic EL elements are very sensitive to moisture and oxygen, and if the organic EL elements are exposed to the atmosphere, there is a possibility that an unlumious area (dark spot) may be generated or the luminance may be reduced because of the moisture and oxygen contained in the atmosphere.
In particular, the organic EL display includes an interlayer insulating film formed so as to cover a drive circuit using a thin-film transistor, and the organic EL elements are arranged on the interlayer insulating film. In this case, an organic insulating film is used as the interlayer insulating film, which functions as a planarizing film for reducing the height of a step caused by the formation of the drive circuit to form the organic EL elements on a planarized surface. However, the interlayer insulating film formed of an organic material is less impermeable to moisture and oxygen, so that the moisture and oxygen remaining in the display device in the condition where they are deposited to foreign matter may be easily diffused through the interlayer insulating film.
FIG. 7 is a sectional view of a display device in the existing art. As shown in FIG. 7, the existing art display device includes a support substrate 10 having a display region 1A where a plurality of organic EL elements are arranged to form an EL layer 13 and a peripheral region 1B where a drive circuit for each organic EL element is provided in the periphery of the display region 1A, a seal resin layer 20 formed over the display region 1A and the peripheral region 1B, and an opposed substrate 30 bonded through the seal resin layer 20 to the support substrate 10, thereby sealing the organic EL elements. Further, a circuit forming layer 11 is formed on the support substrate 10, and an organic insulating film 12 is formed on the circuit forming layer 11. Further, a separation groove B is formed through the thickness of the organic insulating film 12 so as to surround the display region 1A (see Japanese Patent Laid-open No. 2006-54111, for example). Further, the EL layer 13 is formed on the organic insulating film 12 in the display region 1A, and an inorganic insulating film 14 is formed on the organic insulating film 12 so as to cover the EL layer 13 and the inner wall of the separation groove B.
Owing to the formation of the separation groove B through the thickness of the organic insulating film 12, it is possible to prevent that the moisture and oxygen remaining in the outer portion of the organic insulating film 12 outside of the separation groove B may pass through the organic insulating film 12 to enter the inner portion of the organic insulating film 12 inside of the separation groove B, thereby preventing a deterioration of the organic EL elements due to the diffusion of the moisture remaining in the display device.